actinoid actinoid /ˈækˌtɪnɔɪd/

adjective

1. Having a radial form  ( actinoid )
   having a radial form
    Starfish are actinoid--that is, they are radially symmetrical
   starfish are actinoid--that is, they are radially symmetrical
   

noun

1. Any of a series of radioactive elements with atomic numbers 89 through 103  ( actinide , actinoid , actinon )
   any of a series of radioactive elements with atomic numbers 89 through 103